ORAU TEAM

Dose Reconstruction

Project for NIOSH

Oak Ridge Associated Universities I Dade Moeller I MJW Technical Services

Page 1 of 11

DOE Review Release 02/02/2011

Document Title:

Feasibility of Reconstructing Doses 

Received from Potential Exposures to 

Polonium at Savannah River Site

Document Number: ORAUT-RPRT-0048

Revision: 00

Effective Date: 01/24/2011

Type of Document: Report

Supersedes: None

Subject Expert(s): James M. Mahathy

Site Expert(s): Melton H. Chew 

Approval: Signature on File Approval Date: 01/20/2011

James M. Mahathy, Document Owner

Concurrence: Signature on File Concurrence Date: 01/20/2011

James P. Griffin, Deputy Project Director

Concurrence: Signature on File Concurrence Date: 01/20/2011

Kate Kimpan, Project Director

Approval: Signature on File Approval Date: 01/24/2011

James W. Neton, Associate Director for Science

New Total Rewrite Revision Page Change

FOR DOCUMENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE, REPLACE THE PRIOR 

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-RPRT-0048 Revision No. 00 Effective Date: 01/24/2011 Page 2 of 11

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

01/24/2011 00 This report describes activities performed by the Savannah River Site 

(SRS) related to the design of processes and facilities for separating 

210Po from 210Bi with the objective of determining the feasibility of 

reconstructing internal and external doses potentially received from 

exposures to polonium. Incorporates NIOSH formal review 

comments. Training required: As determined by the Objective 

Manager. Initiated by James M. Mahathy. 
Document No. ORAUT-RPRT-0048 Revision No. 00 Effective Date: 01/24/2011 Page 3 of 11

TABLE OF CONTENTS

SECTION TITLE

Acronyms and Abbreviations ...............................................................................................................

PAGE

4

1.0 Summary .................................................................................................................................5

2.0 Introduction ..............................................................................................................................5

3.0 Laboratory-Scale Project..........................................................................................................5

4.0 Pilot Plant and Production Initiatives ........................................................................................6

5.0 Other Laboratory Work.............................................................................................................7

6.0 Feasibility of Dose Reconstruction ...........................................................................................7

References ..........................................................................................................................................9

LIST OF TABLES

TABLE TITLE

3-1 Summary of activities, polonium separation program ...............................................................

PAGE

8
Document No. ORAUT-RPRT-0048 Revision No. 00 Effective Date: 01/24/2011 Page 4 of 11

ACRONYMS AND ABBREVIATIONS

AED Atomic Energy Division

o

C degrees Centigrade

Cu curie

d day

g gram

in. inch

kg kilogram

MeV mega-electron volt

mg milligram

NASA National Aeronautics and Space Administration 

NIOSH National Institute for Occupational Safety and Health

SRDB Site Research Database

SRL Savannah River Laboratory

SROO Savannah River Operations Office

SRS Savannah River Site

yr year
Document No. ORAUT-RPRT-0048 Revision No. 00 Effective Date: 01/24/2011 Page 5 of 11

1.0

This report describes activities performed by the Savannah River Site (SRS) related to the design of 

processes and facilities for separating 210Po from 210Bi with the objective of determining the feasibility 

of reconstructing internal and external doses potentially received from exposures to polonium. A 

smaller project was performed in 1967 to test perovskite mixed oxides as host lattices for a fully 

oxidized 210Po fuel form.

SUMMARY

This report does not provide models for assessing external and internal exposures; those will be 

published in a revision to the SRS site profile document (ORAUT 2005). To perform this analysis, the 

National Institute for Occupational Safety and Health (NIOSH) considered documentation stored in the 

NIOSH Site Research Database (SRDB) and interviewed a former SRS research engineer. NIOSH 

has determined that work to separate 210Po from irradiated bismuth was carried out only in a 

laboratory-scale project conducted in a glovebox. Other work in support of moving to full production 

was performed with the use of stand-in chemicals such as cadmium. NIOSH determined that workers 

involved in the laboratory-scale project were monitored for internal and external exposures (electron 

and photon). Therefore, NIOSH finds that worker doses from potential exposures to polonium can be 

reconstructed.

2.0

SRS first discussed potential separation of 210Po with the U.S. Atomic Energy Commission Savannah 

River Operations Office (SROO) in the early 1960s (Morris 1963). The 210Po was intended for use by 

National Aeronautics and Space Administration (NASA) programs. SROO approved a laboratoryscale project for SRS to provide equipment and to develop a vacuum distillation separation process. 

While the laboratory-scale project was being ramped up, SRS engineers designed a production 

separation facility; the ultimate goal was to move to production separation of up to 3 g of 210Po per day 

(10 kg/yr) (DuPont 1964). For additional verification, SRS operated a pilot plant operation with higher 

throughput than the laboratory-scale project.

INTRODUCTION

3.0

On May 26, 1964, SRS was authorized by SROO to prepare a laboratory for designing and testing a 

program for separating 210Po from irradiated bismuth by vacuum distillation (DuPont 1964) for use in 

the space program (Mahathy 2010). The authorization called for setting up the laboratory in Building 

773-A, Room B-102, with construction work to be completed by December 5, 1964. The intent of the 

laboratory project was to derive experimental quantities of bismuth with a 210Po yield of 0.3 g per trial. 

The authorization stated that no further containment facilities would be required for completion of the 

development work (DuPont 1964); however, NIOSH has no documentation on when the work to 

prepare Room B-102 was completed.

LABORATORY-SCALE PROJECT

Designed air-tight containment was required for the laboratory-scale work because of the extremely 

high alpha activity (4,500 Cu/g) and the volatility of the 210Po. SRS fabricated a two-compartment 

glovebox of stainless steel and safety glass in Room B-102 for use in the 210Po program. The 

glovebox was supported by an understructure. Two bag ports were added (16- and 18-in.) along with 

an exhaust system and services such as electricity and piping. The glovebox was installed adjacent 

to an existing hood that was modified for use with the two ports (DuPont 1964). After initial 

completion of the glovebox, a distilling device was installed using a 2-in.-diameter still with tantalum 

liners (Mahathy 2010; Bradley, Landon, and Gibson 1970). The glovebox contained heavy, flexible 

Hypalon gloves.

The laboratory-scale project was started in 1965 under the guidance of a research engineer working 

with two laboratory technicians. The vacuum distillation process was first documented in 1966 
Document No. ORAUT-RPRT-0048 Revision No. 00 Effective Date: 01/24/2011 Page 6 of 11

(Bradley, Landon, and Gibson 1970). The process was tested using chemical stand-ins for polonium, 

including cadmium and magnesium (Bradley, Landon, and Gibson 1970). The research engineer was 

brought into the laboratory-scale project in June 1966. Three SRS managers/supervisors were 

involved in the project but did not routinely enter Room B-102. The research engineer occupied an 

office (Room B-104) next door to Room B-102. At least one of the workers, the research engineer, 

visited Mound Laboratory for about a week in 1966 to observe operations involving 210Po (Mahathy

2010).

After irradiation of bismuth metal, molten bismuth was transferred for chemical decanting. First, the 

molten metal flowed through an underflow weir to trap slag; then it flowed through a valve that could 

be closed by freezing the metal. The molten bismuth was held for several hours in a tantalum getter 

bed at 750o

C, which removed entrained bismuth oxide and dissolved oxygen. All distilling work 

performed with 210Po in the laboratory-scale project was done in the containment of the glovebox, 

piping, and exhaust venting in Room B-102 (Mahathy 2010). One source stated that up to four trials 

of the dissolution process were conducted in 1967 (Mahathy 2010), which is consistent with the 

number of irradiated bismuth events conducted from February 1, 1967, through May 2, 1967, as part 

of the Curium-II process (Gray 1967). A former research engineer said one trial with 210Po was 

conducted in 1966 with others being done in 1967. It did not begin until 1967 (Mahathy 2010). One 

trial was documented by the Savannah River Laboratory (SRL) to have taken place in June 1968 

(Copley and Moyer 1968a); SRS Health Physics monitored B-102 for exposure and contamination 

(Mahathy 2010). Personnel wore laboratory coats when working in Room B-102. They wore rubber 

gloves taped to the sleeves of their laboratory coats and company-provided shoes or shoe covers that 

were not worn outside Building 773-A. Laboratory personnel performed frequent contamination 

monitoring of their garments, hands, and bodies. SRS Health Physics performed routine surveys of 

Room B-102 (Mahathy 2010). Air sampling was performed in Room B-102 (Mahathy 2010). 

Laboratory personnel did not use respiratory protection, although the research engineer wore such

protection while visiting the Mound Laboratory to work on its polonium process. It was implied that the 

risk of airborne release of polonium was much less with the SRS laboratory-scale process than with 

the Mound process. However, due to the high (5-MeV) alpha energy, polonium could diffuse through 

the Hypalon gloves. To prevent escape of 210Po through the gloves, the laboratory technicians often 

measured inside the Hypalon gloves; the gloves were exchanged in a routine process. Polonium-210 

was not removed from the glovebox in Room B-102 until May 1969, when an estimated 1,400 Cu

were removed by the laboratory technicians and SRS Health Physics, transferred to a concrete waste 

cask without spread of contamination, and shipped to the SRS burial ground (Mahathy 2010; Copley 

and Moyer 1969a).

4.0

Simultaneous with the performance of the laboratory-scale program, SRS planned and prepared to 

build the full production plant that would separate up to 3 g/d of 210Po (10 kg/yr).

PILOT PLANT AND PRODUCTION INITIATIVES

In 1965, SRS published building designs and cost estimates for a new building in the 200-F Area 

north of Building 232-F to house polonium-processing facilities (Daking and Lanci 1965). Equipment 

for the processing of irradiated bismuth metal and the distilling of polonium was to be based on the 

design of, and testing results of, the laboratory-scale equipment. The E. I. du Pont de Nemours and 

Company (the Management and Operations Contractor) Atomic Energy Division (AED) requested that 

an alternative be considered, so in 1966 SRS published a plan for interim polonium-processing 

facilities in the Cold Feed Preparation Area of Building 221-F (Daking and Lanci 1966a,b). By June 

1966, AED had canceled planning for a new building to house polonium processing facilities but was

still directing SRS to prepare budget estimates for the modification of Building 221-F (Daking and 

Lanci 1966c). NIOSH has no documentation to show that modifications were done.
Document No. ORAUT-RPRT-0048 Revision No. 00 Effective Date: 01/24/2011 Page 7 of 11

In 1967, SRS constructed a pilot-scale facility known as SemiWorks in the TNX building. The TNX 

building was used to test processes using reduced-scale models of production designs and no 

radioactive materials (i.e., surrogate materials were used). A distillation device based on the 

laboratory-scale distillation equipment, but with 8-in.-diameter stills, was built in SemiWorks (Mahathy

2010; Bradley, Landon, and Gibson 1970). All testing performed in the pilot-scale program used 

cadmium as a surrogate for 210Po (Mahathy 2010). No work with 210Po was performed in the pilotscale program.

By 1970, AED cancelled plans for the production separation of 210Po from irradiated bismuth due to 

NASA concerns. Rather, heat sources using 238Pu were pursued. A final report of the SRS polonium 

distillation program was published in 1970 (Mahathy 2010).

5.0

The SRS analytical laboratory performed radiochemical analysis of 210Po as early as 1965 in Building 

773-A. A technician was involved in a bench spill of a polonium sample in May 1965. SRS Health 

Physics monitored the spill and performed bioassay on the technician. Additional laboratory analyses 

are documented in 1966 and 1967 (Gray 1967).

OTHER LABORATORY WORK

SRS performed an additional activity to assist the Mound Laboratory in testing 210Po as a candidate 

for fuel capsules for use in aerospace applications. One of the design objectives was to formulate 

and test oxidation-resistant fuel forms of 210Po. The work at SRS included design of containment 

facilities and equipment needed for small-scale research of perovskite, spinel, garnet, fluorite, and 

brookite mixed oxides to investigate systems that would reduce the decomposition pressure and rate 

of loss of polonium that would meet aerospace safety criteria (Hilborn 1967a,b). Mound shipped 

20 mg of 210Po to SRS to use for this particular fuel capsule testing; the quantity is about one-tenth the 

mass quantity of 210Po extracted in a trial mentioned in Section 1. Equipment, including a fume hood, 

was used for the work, which took place in Building 773-A. Nonradioactive tellurium was used as a 

stand-in for 210Po (Hilborn 1967b). Active research with this effort appears to have ceased by the end 

of 1967 because the activity is not mentioned in SRL Isotopic Power and Heat Sources quarterly 

progress reports issued after 1967; however, external exposure rates from 210Po were still being 

measured in December 1968 (Copley and Moyer 1969b).

SRS Health Physics monitored Building 773-A for 210Po contamination and for beta/gamma and 

neutron exposure rates through May 1969 when polonium was removed from the glovebox in Room 

B-102 and buried.

6.0

A summary of tasks performed at SRS to plan and prepare facilities for separation of polonium and 

actual separation work with polonium is presented in Table 3-1.

FEASIBILITY OF DOSE RECONSTRUCTION

As shown in Table 3-1, actual separation of polonium from irradiated bismuth metal was done in 1967 

in a laboratory-scale effort with up to four trials and with one documented trial in 1968. That work was 

performed in a glovebox environment along with routine workplace monitoring (Mahathy 2010). Work 

was performed in a glovebox with a small quantity of 210Po in 1967 to research oxidation-resistant fuel 

forms of 210Po (Hillborn 1967a).

Personnel who entered Room B-102 were monitored for external radiation electron and photon 

exposures by film badge (Mahathy 2010; SRP 1967a,b,c,d). The research engineer and two 

laboratory technicians were sampled twice in 1967 by in vitro bioassay for exposure to 210Po. They 

were first sampled in February 1967 (Author unknown 1967a); which coincides with the first bismuth 

irradiation event of 1967 performed a few days before (Gray 1967). Each of the three was also 
Document No. ORAUT-RPRT-0048 Revision No. 00 Effective Date: 01/24/2011 Page 8 of 11

Table 3-1. Summary of activities, polonium separation program.

Task circa Reference

Discussion of separation of Po-210 with SROO for NASA 

use

1963 Morris 1963

Design and construction of laboratory for laboratory-scale 

separation

1964 DuPont 1964

Vacuum distillation process developed using surrogate 

chemicals

1965–1966 Bradley, Landon, and Gibson 

1970

Design of production separation facilities 1965–1966 Daking and Lanci 1965

Bismuth metal irradiated in Curium-II campaign 1966–1967 Gray 1967

Laboratory-scale separation of Po-210 for irradiated bismuth 1967–1968 Mahathy 2010

Test oxidation-resistant fuel forms for Po fuel capsules 1967 Hilborn 1967a,c

Construction of pilot plant at TNX 1967–1968 Mahathy 2010

Pilot plant separation of cadmium (surrogate) at TNX 1968–1969 Mahathy 2010

Polonium separation program terminated 1969 Mahathy 2010

Final report of polonium separation program published 1970 Bradley, Landon, and Gibson 

1970

sampled in August 1967 (Author unknown 1967b). Some additional results are available for 

September and November 1967. Results of all polonium bioassay results were reported as less than 

detectable.

NIOSH has shown that three people involved in routine daily operations in the laboratory-scale 

separation activities in Room B-102 were sampled for intake of polonium (Mahathy 2010; Author 

unknown 1967a,b). NIOSH has obtained polonium bioassay results for additional SRS workers, all of 

whom worked in Building 773-A. NIOSH concludes that SRS workers with the potential for internal 

intake of polonium were monitored by bioassay. SRS Health Physics monitored locations where 

polonium was used (Copley and Moyer 1968b,c,d; 1969c,d,e) with no events of contamination 

highlighted in monthly reports. Therefore, bioassay data for a claimant can be modeled for intake to 

reconstruct potential doses from polonium. If a claimant does not have polonium bioassay data, 

NIOSH concludes that claimant was not exposed to polonium.

NIOSH has documented that staff members who entered the laboratory-scale laboratory (Room 

B-102) were monitored for external electron and photon exposures. As a consequence, film badge 

data can be used to reconstruct external exposures from polonium (Mahathy 2010).

It is uncertain to NIOSH if all laboratory-scale staff members were monitored for exposure to neutrons. 

Some neutrons could have been produced from concentrated polonium deposited on tantalum due to 

the [α,n] reaction of oxygen impurities in the tantalum liners (Bradley, Landon, and Gibson 1970). 

Neutron shielding was used on the laboratory-scale glovebox. Neutron dose rates taken at 3 in. from 

the glovebox in Room B-102 showed no measureable neutron exposure (Copley and Moyer

1968b,c,d; 1969c,d,e).
Document No. ORAUT-RPRT-0048 Revision No. 00 Effective Date: 01/24/2011 Page 9 of 11

REFERENCES

Author unknown, 1967a, “Po 210 Records 2-7-1967 to 3-22-1967,” Savannah River Plant, Aiken, 

South Carolina. [SRDB Ref ID: 53246]

Author unknown, 1967b, “Po 210 Records 4-7-1967 to 3-22-1967,” Savannah River Plant, Aiken, 

South Carolina. [SRDB Ref ID: 53247]

Bradley, R. F., L. F. Landon, and G. W. Gibson, 1970, Separation of 210Po from Bismuth by Liquid 

Metal Distillation, DP-1222, E. I. du Pont de Nemours and Company, Savannah River 

Laboratory, Aiken, South Carolina, June. [SRDB Ref ID: 48630]

Copley, B. C., and R. A. Moyer, 1968a, Monthly Report June 1968, DPST-68-93-6, E. I. du Pont de 

Nemours and Company, Savannah River Laboratory, Radiological Sciences Division, Aiken, 

South Carolina, July 3. [SRDB Ref ID: 75600]

Copley, B. C., and R. A. Moyer, 1968b, Monthly Report August 1968, DPST-68-93-8, E. I. du Pont de 

Nemours and Company, Savannah River Laboratory, Radiological Sciences Division, Aiken, 

South Carolina, September 5. [SRDB Ref ID: 75605]

Copley, B. C., and R. A. Moyer, 1968c, Monthly Report September 1968, DPST-68-93-9, E. I. du Pont 

de Nemours and Company, Savannah River Laboratory, Radiological Sciences Division, 

Aiken, South Carolina, October 4. [SRDB Ref ID: 75608]

Copley, B. C., and R. A. Moyer, 1968d, Monthly Report October 1968, DPST-68-93-10, E. I. du Pont 

de Nemours and Company, Savannah River Laboratory, Radiological Sciences Division, 

Aiken, South Carolina, November 4. [SRDB Ref ID: 75609]

Copley, B. C., and R. A. Moyer, 1969a, Monthly Report May 1969, DPST-69-93-5, E. I. du Pont de 

Nemours and Company, Savannah River Laboratory, Radiological Sciences Division, Aiken, 

South Carolina, June 4. [SRDB Ref ID: 48639]

Copley, B. C., and R. A. Moyer, 1969b, Monthly Report December 1968, DPST-68-93-12, E. I. du 

Pont de Nemours and Company, Savannah River Laboratory, Radiological Sciences Division, 

Aiken, South Carolina, January 7. [SRDB Ref ID: 75616]

Copley, B. C., and R. A. Moyer, 1969c, Monthly Report January 1969, DPST-69-93-1, E. I. du Pont de 

Nemours and Company, Savannah River Laboratory, Radiological Sciences Division, Aiken, 

South Carolina, February 6. [SRDB Ref ID: 48636]

Copley, B. C., and R. A. Moyer, 1969d, Monthly Report February 1969, PST-69-93-2, E. I. du Pont de 

Nemours and Company, Savannah River Laboratory, Radiological Sciences Division, Aiken, 

South Carolina, March 5. [SRDB Ref ID: 48637]

Copley, B. C., and R. A. Moyer, 1969e, Monthly Report April 1969, DPST-69-93-4, E. I. du Pont de 

Nemours and Company, Savannah River Laboratory, Radiological Sciences Division, Aiken, 

South Carolina, May 5. [SRDB Ref ID: 48638]

Daking, E. A., and A. Lanci, 1965, Work Request 850867-10 – Savannah River Plant Polonium-210 

Processing Facilities Process Scope of Work for Current Appraisal of Cost Estimate, E. I. du 

Pont de Nemours and Company, September 16. [SRDB Ref ID: 67939]
Document No. ORAUT-RPRT-0048 Revision No. 00 Effective Date: 01/24/2011 Page 10 of 11

Daking, E. A., and A. Lanci, 1966a, Work Request 850867-10 – Savannah River Plant Polonium-210 

Interim Processing Facilities Process Scope of Work for Current Appraisal of Cost Estimate 

Case I, E. I. du Pont de Nemours and Company, March 14. [RDB Ref ID: 67943]

Daking, E. A., and A. Lanci, 1966b, Work Request 850867-10 – Savannah River Plant Polonium-210 

Interim Processing Facilities Process Scope of Work for Current Appraisal of Cost Estimate 

Case I, E. I. du Pont de Nemours and Company, March 18. [SRDB Ref ID: 67945]

Daking, E. A., and A. Lanci, 1966c, Work Request 850867 – Savannah River Plant Polonium-210 

Interim Processing Facilities Process Scope of Work for Current Appraisal of Cost Estimate All 

Functions, E. I. du Pont de Nemours and Company, June 27. [SRDB Ref ID: 67948]

DuPont (E. I. du Pont de Nemours and Company), 1964, Polonium Recovery Facility, Building 773-A, 

Atomic Energy Division, Savannah River Plant, Aiken, South Carolina. [SRDB Ref ID: 68029, 

pp. 7-8]

Gray, P. L., 1967, “Polonium Production in Curium-II,” DPSP-67-1281, memorandum to L. W. Fox,

E. I. du Pont de Nemours and Company, Savannah River Plant, Aiken, South Carolina, June 

30. [SRDB Ref ID: 49819]

Hilborn, H. S., 1967a, Savannah River Laboratory Isotopic Power and Heat Sources Quarterly 

Progress Report, April - June 1967 Part II, Curium-244, Polonium-210, and Thulium-170 and 

-171, DP-1120-II, E. I. du Pont de Nemours and Company, Savannah River Laboratory, Aiken, 

South Carolina, August. [SRDB Ref ID: 49317, pp. 2-24]

Hilborn, H. S., 1967b, Savannah River Laboratory Isotopic Power and Heat Sources Quarterly 

Progress Report, July - September 1967, Part II, Curium-244, Polonium-210, and Thulium-170 

and -171, DP-1129-II, E. I. du Pont de Nemours and Company, Savannah River Laboratory, 

Aiken, South Carolina, August. [SRDB Ref ID: 49343, pp. 2-25]

Hilborn, H. S., 1968, Savannah River Laboratory Isotopic Power and Heat Sources Quarterly 

Progress Report, October -December 1967, Part II Curium-244, Plutonium-238, Polonium-210, 

and Thulium-170, DP-1143-II, E. I. du Pont de Nemours and Company, Savannah River 

Laboratory, Aiken, South Carolina, February. [SRDB Ref ID: 49344, pp. 2-50]

Mahathy, M., 2010, SRS Po-210 Project (Documented Communication with Foster Bradley), Oak 

Ridge Associated Universities Team, Oak Ridge, Tennessee, September 24. [SRDB Ref ID: 

88135]

Morris, J. W., 1963, “Polonium Separations,” memorandum to L. C. Evans, E. I. du Pont de Nemours 

and Company, Savannah River Laboratory, Technical Division, Aiken, South Carolina, 

November 27. [SRDB Ref ID: 58512]

ORAUT (Oak Ridge Associated Universities Team), 2005, Savannah River Site, ORAUT-TKBS-0003, 

Rev. 02, Oak Ridge, Tennessee, April 5.

SRP (Savannah River Plant), 1967a, Dosimetry Quarterly Report for Period Ending March 1967, E. I. 

du Pont de Nemours and Company, Aiken, South Carolina, April 17. [SRDB Ref ID: 50063]

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du Pont de Nemours and Company, Aiken, South Carolina, July 25. [SRDB Ref ID: 50064]
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SRP (Savannah River Plant), 1967c, Dosimetry Quarterly Report for Period Ending September 1967,

E. I. du Pont de Nemours and Company, Aiken, South Carolina, July 25. [SRDB Ref ID: 

50061]

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